Well, setting x-www-browser to mozilla,
Getting about.config and editing the two values to mozilla
:-(
Clicking on a URL does zip...
Are you running Gnome or KDE? If so, TB might be passing off the
request to the desktop environment instead of using the value you
specified. I'm running Fvwm, so I don't have experience in getting
this behavior to work in a "better" windowing environment. I remember
I found the solution that worked for me through googling. I believe
there were Gnome/KDE instructions provided as well. Try
http://www.google.com/search?q=thunderbird+open+URL